Electronics

Central New York (CNY) Engineering Expo

Nov 13th, 2017

Summary

Globe is proud to sponsor The Central New York Engineering Expo (CNY Expo). Karl Wiegand, a Technical Education and Research Engineer at Globe, will be presenting for the benefit of your continued education credits (CESs).

Description

1) Since the 1985 Edition of NFPA 13 a means of pressure relief has been required in gridded sprinkler systems. In 2010 this requirement was changed to require a listed pressure relief valve in all wet pipe systems: not only gridded systems. These requirements have been put in place to help prevent system over-pressurization. Thermal expansion is one of the main causes of system over-pressurization. This presentation will address how the properties of thermal expansion impact system pressures as well as the relationships of the different variables in the thermal expansion equation. It will explain how piping material, liquid, and available air cushion affect thermal expansion. It will show where pressure relief valves are required to help mitigate the effects of thermal expansion and where they may be needed even when they are not required by the installation standards.

Learning Objectives:

· Identify the properties of thermal expansion

· Recognize the difference in thermal expansion between different piping materials and liquids

· Apply air vent requirements for NFPA 13 and identify how they affect thermal expansion

· Apply pressure relief valve requirements for NFPA 13 and recognize other condition where they may be needed

2) Dry pipe valves have historically been differential style valves to allow a lower amount of system air pressure to hold back a larger amount of water pressure in the system supply. Traditionally, though this differential exists, dry sprinkler systems have always required a fairly significant amount of air pressure. With new technology developments, low-pressure dry pilot actuators have allowed a lower amount of air pressure to hold back the water pressure in the system supply. With these developments, the concept has been embraced that a lower air pressure system is better for fire protection. The idea is that lower air pressure in a dry pipe system will allow the air pressure in the system to evacuate quicker which will, in turn, allow the system to fill with water quicker and thus provide water to the fire quicker. However, this is not always the case. This presentation is intended to differentiate when and why it is more advantageous to maintain a higher system air pressure versus the use of low air pressure in the in the system.

Learning Objectives:

· Recognize the key factors that affect dry pipe system trip times

· Distinguish the differences between a low-pressure dry pipe system and a high-pressure dry pipe system

· Recognize whether dry pipe system characteristics favor a low pressure or a high-pressure system

· Identify the proper types of dry pipe systems to use to achieve the fastest trip times